ehrman



nu. s|9,4s9. rammed Feb. I4, |899.

E. H. Enma-AN.

SEAT POST CLAMP.

(Ayplicntinn ledpec. 23, 1897.)

(no Model.)

ma muws Pirens co.. mowmwo., WAsNrNaYoN. n` l:

NTTED STATESN PATENT FFICE.

EDWIN II. EHRMAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WALKER a EHRMANMANUFACTURING COMPANY, OF SAME PLACE.

SPECIFICATION forming parl'. 0f Letters Patent N0. 619,469, (fla/tedFebruary 14, 1899.

Application led DecemherZS, 1897. Serial No. 663,166. (No model.)

To all whom t may concern:

Be it known that I, EDWIN H. EHRMAN, a citizen of the United States,residing in Chicago, in the county of Cook and State of Illinois, haveinvented a new and useful Improvement in Seat-Post Clamps, of which thefollowing is a specification.

This invention relates to an improved construction of seat-post clamp;and it consists of the combination, with the seat-post and theframe-tube receiving it, of an inner thimble contractible at both endsand made abruptly tapering at its top and gently tapering at its bottom,an outer thimble eXpansible at its lower end and made taperinginternally to correspond with the taper of the lowerend of the innerthimble and threaded at its upper end and also provided with a shoulderto engage the upper end of the frame-tube, and a screw-cap covering boththimbles and engaging the thread of the outer one and acting to forcethe inner one downward, and thus to eX- pand the lower end of the outerthimble and at the same time contract the upper end of the outerthimble, so as to irmly hold the post at both the upper and lower endsof the clamp. l

The nature of this improvement will be better understood from theaccompanying drawings, in which- Figure l is a side elevation of thedevice as applied to a bicycle. Fig. 2 is an enlarged vertical sectionof the clamp,showing the post in position therein. Figs. 3 and 4 areelevations of the inner and outer thimbles, respectively. Fig. 5 is asection on the line 5 5 of Fig. 2. Figs. 6 and 7 illustrate modications.

In said drawings, A represents the seatpost, and B the frame-tube inwhich it is inserted.

C is the inner thimble and is slit throughout its length, as seen at C',and is also provided with other slits C2, extending upward from itsbottom for only a portion of its length. At its upper end it is abruptlytapering, as seen at C3, and at its lower end it is made gently taperingin areverse direction from its uppertaper, as seen at C4. The outerthimble is shown at D, and it is also slit froln the bottom upward for aportion of its length, as at D'. At its upper end it is threaded, as atD2,

and adjacent to this -threaded portion is an annular shoulder D3, whichrests upon the upper end of the frame-tube B. lnteriorly at its lowerend the thimble D is made tapering in the reverse direction from thetaper C4 of the inner thimble. This will be linderstood from Fig. 2,where the taper is clearly shown at D4. It will be seen from thisconstruction that the inner thimble is contracti- 6o ble at both endsand that the outer thimble is expansible at its lower end; also, thatwhen the inner thimble is forced downward it will expand the outerthimble against the inner surface of the frame-tube. The cap is 6 5shown at E. It is threaded interiorly to engage the thread D2 of theouter thimble and also provided with a beveled interior surface E',corresponding to the bevel C3 of the innerV thimble. With thisconstruction of the parts 7o of. the clamp it will be seen that whenthey are assembled, as clearly indicated at Fig. 2, the cap is adaptedto force the inner thimble downward, so as to cause the expansion of thelower end of the outer thimble against the inner surface oftheframe-tube B. Atthe same time that this expansion of the outerthimble occurs a reiieX action is caused upon the inner thimble, whichcontracts the lower end of that thimble against the seat-post, so the 8ol post is held very rmly in the plane of the lower ends of the thimbles.When the downward movement of the inner thimble stops by reason of thecompression thus caused at its lower end, the screw-cap will then act tocontract the upper end of the inner thimble `against the post, so as tohold the latterin the plane of the upper ends of the thimbles. While thepost is thus clamped by both ends ofthe inner thimble both the clamp andpost 9o are supported by the shoulder D3, and the friction by the outerthimble upon the inner surface of the tube is sufficient to hold theparts stationary in the tube.

It will be noticed that while the taper at the lower ends of thethimbles is slight it is not so much so as to prevent the withdrawal ofthe post by an upward pull thereon after the cap is unscrewecl, and itis rendered unnecessary to attach the cap to the inner thirn- 10o ble soit may actuate the latterin both directions; also, that the innerthimble is cylindrical between its conical or tapering portions, andthat such cylindrical portion enables the separation of the more activeclamping portions of the thimble for any desired distance, so that thepost can be afforded a Wide bearing.

Instead of holding the outer thimble in the frame-tube by friction inthe manner described said thiinble may be made non-expansible and bebrazed or otherwise secured to the tube, or the outer thimble may bewholly dispensed with, and the in ner `taper D4 thereof may be madeintegral with the frame member. These modiications are shown at Figs. 6and 7.

While I have shown'and described the invention as applied to aseat-post, it will be understood that it may be used in securinghandle-bars to the steering-posts of bicycles, and, in fact, it may beused Whenever two parts, one of which is provided with a cylindricalsocket into which the other enters, are to be detachably united.

I claiml. The combination in a seat-post clamp of a contractible andlongitudinally-movable thimble encircling the post and made re- Verselytapering at its ends, the taper at one end being abrupt and that at theother end being gentle, an outer thirnble tapered interiorly tocorrespond to the gently-tapered end of the inner thimble and acting tocompress that end when the inner thimble is moved 1ongitudinally, and acap actin g on the abruptlytapered end and causing both the contractionof that end and the longitudinal movement, substantially as specified.

2. The combination in a clamp-joint for adjustably securing together twoparts, one of which enters Within the other, the combination of acontractible and longitudinallymovable inner thimble abruptly taperingat one end and gently tapering at the other end, an outer expausiblethirnble tapering interiorly to correspond With the gentle taper of theinner thimble, and a cap threaded on the outer thimble and acting on theabruptly-tapered end of the inner thimble and causing rst a longitudinalmovement of said inner thirnble and a consequent compression of itslower end, and then a compression of its upper end, substantially asspecified.

EDWIN I'I. EI-IRMAN.

Witnesses:

H. M. MUNDAY, S. E. CURTIS.

